1. Field of the Invention
The present invention relates to an automotive actuator retaining construction for retaining an actuator such a slave cylinder or servo which is used in operating brakes and a transmission clutch of an automotive vehicle in a retracted state and releasing the retracted state.
2. Description of the Related Art
Conventionally, for example, a clutch master cylinder and a slave cylinder or servo which are used as actuators for operating a transmission clutch of an automotive vehicle are connected to each other using pipings as a clutch piping system in a layout substantially equal to that resulting when they are actually installed on an automotive vehicle and then hydraulic operating fluid is filled in the system before they are shipped from a manufacturer, and thus clutch piping systems are shipped to an assembling plant of a car manufacturer in a so-called pre-fluid-filled state.
Of the two cylinders, the slave cylinder or servo is constructed such that a piston rod thereof extends into or retracts from a housing by virtue of movement of pressurized fluid from the clutch master cylinder which is a source for generating a hydraulic pressure. In the aforesaid pre-fluid-filled state, in order to prevent the piston rod from rattling, a retaining construction is used to retain the piston rod in a retracted state. Retaining constructions like this are disclosed, for example, in JP-B-4-8644 and JP-A-9-32805.
In the former retaining construction, a retaining belt-like string is extended between the housing of a slave cylinder and a projecting end of a piston rod so that the piston rod is retained in a state in which the piston rod is retracted in a direction toward the housing, and the retaining belt-like string is constructed to be cut at a lowered-strength portion provided therein when an actuator is first operated after the clutch piping system is installed on an automotive vehicle.
Alternatively, in the latter retaining construction, a plurality of legs are provided on a protection boot for covering between the housing of a slave cylinder and a projecting end of a piston rod, for retaining a bellows portion in a retracted state. Further, in the legs, there are provided lowered-strength portions which are constructed to be broken by virtue of a projecting force of the piston rod.
In these retaining constructions, however, since the load required for operating the clutch pedal so as to tear the retaining belt-like string and the legs of the protection boot also acts on seals of the actuator and the protection boot to thereby impose an unnecessary load thereon, the construction is not desirable. In addition, burrs and broken particles are generated on cut surfaces of the retaining belt-like string and the legs, and these cause problems in servicing the actuator for maintenance thereof. Moreover, the retaining belt-like string and the legs which are cut or broken continue to suspend and this deteriorates the external appearance of the relevant portion of the automotive vehicle.
The invention was made to cope with these problems and an object thereof is to provide an automotive actuator retaining construction for retaining a piston rod of an actuator for use in a braking system or a transmission clutch in a retracted state from filling a clutch piping system with a hydraulic fluid at the time of manufacture until installing the clutch piping system on an automotive vehicle, while securely avoiding suffering from the aforesaid problems.
With a view to attaining the aforesaid object, according to a first aspect of the invention, there is provided an automotive actuator retaining construction adapted to retain a piston rod accommodated in a housing of an actuator in an extensible or retractable fashion in a state in which the piston rod is retracted in a direction toward the housing and to release the piston rod from the retracted state so as to permit the extension and/or retraction of the piston rod when the actuator is put in operation, the automotive actuator retaining construction comprising a first retainer adapted to be mounted on one of the housing and the piston rod and a second retainer adapted to be mounted on the other, wherein at least the first retainer is adapted to be removed from the one of the housing and the piston rod, and wherein the first and second retainers are connected to each other in such a manner as to be disengaged from each other, whereby in a state in which the first and second retainers are in engagement with each other, the retracted state of the piston rod is maintained, whereas the engagement between the first and second retainers is released by removing the first retainer from the one of the housing and the piston rod, the piston rod being thereby permitted to extend and/or retract.
According to the construction, the retracted state of the piston rod is retained by virtue of the connection of the first and second retainers, and the engagement state of the first and second retainers is released by removing the first retainer from one of the housing and the piston rod, whereby the piston rod extends from the housing, the piston rod being thereby permitted to extend and/or retract.
In addition, at least the first retainer is assembled in such a manner as to be removed from the one of the housing and the piston rod, but the invention may not prevent the second retainer from falling from the other of the housing and the piston rod as a result of the disengagement of the second retainer from the first retainer.
According to a second aspect of the invention, there is provided an automotive actuator retaining construction as set forth in the first aspect of the invention, wherein the first retainer comprises an assembling unit adapted to be mounted on one of the housing and the piston rod in such a manner as to be disengaged therefrom, a plurality of connecting legs disposed so as to extend along the one of the housing and the piston rod and first engagement portions formed at distal ends of the respective connecting legs, and wherein the second retainer comprises second engagement portions adapted to engage with and disengage from the first engagement portions.
According to a third aspect of the invention, there is provided an automotive actuator retaining construction as set forth in the second aspect of the invention, wherein the assembling unit of the first retainer surrounds one of the housing or the piston rod and is formed into a C shape having a slit for removal of the first retainer in a certain part thereof. According to a fourth aspect of the invention, there is provided an automotive actuator retaining construction as set forth in the second or third aspect of the invention, wherein the plurality of connecting legs are connected to each other by a lateral belt holding one of the housing and the piston rod in a circumferential direction. According to a fifth aspect of the invention, there is provided an automotive actuator retaining construction as set forth in the fourth aspect of the invention, wherein a breakable portion is provided on the lateral belt which is designed to break when the first retainer is removed.
According to a sixth aspect of the invention, there is provided an automotive actuator retaining construction as set forth in any of the aspects 2 to 5, wherein the engagement of the first and second retaining portions regulates an axial movement of the piston rod.